The present embodiments relate to monitoring a temporal change in a magnetic field in a magnetic resonance device.
During the magnetic resonance measurement (e.g., during the performance of Magnetic Resonance Imaging (MRI)) of a patient, rapidly switched gradient pulses are customarily applied by a magnetic resonance device, and gradient fields are thus generated. The magnetic resonance device customarily has a gradient coil unit with a plurality of gradient coils to generate the gradient fields. Usually, the magnetic resonance device includes three gradient coils that are configured to generate magnetic field gradients perpendicular to each other (e.g., an x-gradient coil that may generate a magnetic field gradient in an x-direction, a y-gradient coil that may generate a magnetic field gradient in a y-direction, and a z-gradient coil that may generate a magnetic field gradient in a z-direction).
The gradient pulses may produce Peripheral Nerve Stimulation (PNS) in the patient's body as soon as certain field change thresholds are exceeded. In a study of patients with implants (e.g., neurostimulators and/or cardiac pacemakers), there are particularly high risks, such as, for example, tachycardia as a result of stimulation of the heart and/or burns of nervous tissue. Therefore, standardization bodies require monitoring and/or restriction of field change. For example, in a magnetic resonance scan of implant wearers, the IEC 60601-2-33 standard provides that a temporal change in a magnetic field in a magnetic resonance device may not exceed a peak value |dB/dt|PEAK,limit of 100 T/s and an average value |dB/dt|RMS,limit of 56 T/s.